A regular thymine tetrad and a peculiar supramolecular assembly in the first crystal structure of an all-LNA G-quadruplex. Krauss, I. R., Parkinson, G. N., Merlino, A., Mattia, C. A., Randazzo, A., Novellino, E., Mazzarella, L., & Sica, F. Acta crystallographica. Section D, Biological crystallography, 70(Pt 2):362–70, February, 2014. Publisher: International Union of Crystallography
A regular thymine tetrad and a peculiar supramolecular assembly in the first crystal structure of an all-LNA G-quadruplex. [link]Paper  doi  abstract   bibtex   
Locked nucleic acids (LNAs) are formed by bicyclic ribonucleotides where the O2' and C4' atoms are linked through a methylene bridge and the sugar is blocked in a 3'-endo conformation. They represent a promising tool for therapeutic and diagnostic applications and are characterized by higher thermal stability and nuclease resistance with respect to their natural counterparts. However, structural descriptions of LNA-containing quadruplexes are rather limited, since few NMR models have been reported in the literature. Here, the first crystallographically derived model of an all-LNA-substituted quadruplex-forming sequence 5'-TGGGT-3' is presented refined at 1.7 Å resolution. This high-resolution crystallographic analysis reveals a regular parallel G-quadruplex arrangement terminating in a well defined thymine tetrad at the 3'-end. The detailed picture of the hydration pattern reveals LNA-specific features in the solvent distribution. Interestingly, two closely packed quadruplexes are present in the asymmetric unit. They face one another with their 3'-ends giving rise to a compact higher-order structure. This new assembly suggests a possible way in which sequential quadruplexes can be disposed in the crowded cell environment. Furthermore, as the formation of ordered structures by molecular self-assembly is an effective strategy to obtain nanostructures, this study could open the way to the design of a new class of LNA-based building blocks for nanotechnology.
@article{krauss_regular_2014,
	title = {A regular thymine tetrad and a peculiar supramolecular assembly in the first crystal structure of an all-{LNA} {G}-quadruplex.},
	volume = {70},
	issn = {1399-0047},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/24531470},
	doi = {10.1107/S1399004713028095},
	abstract = {Locked nucleic acids (LNAs) are formed by bicyclic ribonucleotides where the O2' and C4' atoms are linked through a methylene bridge and the sugar is blocked in a 3'-endo conformation. They represent a promising tool for therapeutic and diagnostic applications and are characterized by higher thermal stability and nuclease resistance with respect to their natural counterparts. However, structural descriptions of LNA-containing quadruplexes are rather limited, since few NMR models have been reported in the literature. Here, the first crystallographically derived model of an all-LNA-substituted quadruplex-forming sequence 5'-TGGGT-3' is presented refined at 1.7 Å resolution. This high-resolution crystallographic analysis reveals a regular parallel G-quadruplex arrangement terminating in a well defined thymine tetrad at the 3'-end. The detailed picture of the hydration pattern reveals LNA-specific features in the solvent distribution. Interestingly, two closely packed quadruplexes are present in the asymmetric unit. They face one another with their 3'-ends giving rise to a compact higher-order structure. This new assembly suggests a possible way in which sequential quadruplexes can be disposed in the crowded cell environment. Furthermore, as the formation of ordered structures by molecular self-assembly is an effective strategy to obtain nanostructures, this study could open the way to the design of a new class of LNA-based building blocks for nanotechnology.},
	number = {Pt 2},
	journal = {Acta crystallographica. Section D, Biological crystallography},
	author = {Krauss, Irene Russo and Parkinson, Gary Nigel and Merlino, Antonello and Mattia, Carlo Andrea and Randazzo, Antonio and Novellino, Ettore and Mazzarella, Lelio and Sica, Filomena},
	month = feb,
	year = {2014},
	pmid = {24531470},
	note = {Publisher: International Union of Crystallography},
	keywords = {\#nosource, Crystallography, G-Quadruplexes, Models, Molecular, Oligonucleotides, Oligonucleotides: chemistry, Thermodynamics, Thymine, Thymine: chemistry, X-Ray},
	pages = {362--70},
}

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